# sha1

Calculate SHA-1 hash of a string

Agent View of the PolicyLayer registry record for `sha1`. HTML page: https://policylayer.com/tools/1595901624-crypto-mcp/sha1

## Facts

- Tool: `sha1`
- Server: Crypto_MCP (`1595901624/crypto-mcp`) — https://policylayer.com/tools/1595901624-crypto-mcp.md
- Homepage: https://github.com/1595901624/crypto-mcp
- Risk category: Read (Low risk)
- Registry record: grade A, identity unverified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Allowed

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "sha1",
    "arguments": {}
  }
}
```

## Why sha1 is rated Low

SHA-1 hashing is a read-only operation that retrieves a deterministic hash value from input. It has no side effects on data (non-reversible by design, but not destructive of the original), does not execute arbitrary code or commands, and does not move money or create/modify persistent data.

From the tool's own definition: "The tool 'Calculate SHA-1 hash of a string' performs a one-way cryptographic hashing operation that produces a fixed-length output from input data without modifying, deleting, or executing external operations."

## Use case

AI agents call sha1 to retrieve information from Crypto_MCP without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Crypto_MCP:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "sha1": {}
  }
}
```

## Other tools on Crypto_MCP (13)

- `des_encrypt` — Execute — https://policylayer.com/tools/1595901624-crypto-mcp/des-encrypt.md
- `aes_encrypt` — Other — https://policylayer.com/tools/1595901624-crypto-mcp/aes-encrypt.md
- `aes_decrypt` — Read — https://policylayer.com/tools/1595901624-crypto-mcp/aes-decrypt.md
- `base64_decode` — Read — https://policylayer.com/tools/1595901624-crypto-mcp/base64-decode.md
- `base64_encode` — Read — https://policylayer.com/tools/1595901624-crypto-mcp/base64-encode.md
- `des_decrypt` — Read — https://policylayer.com/tools/1595901624-crypto-mcp/des-decrypt.md
- `hex_decode` — Read — https://policylayer.com/tools/1595901624-crypto-mcp/hex-decode.md
- `hex_encode` — Read — https://policylayer.com/tools/1595901624-crypto-mcp/hex-encode.md
- `md5` — Read — https://policylayer.com/tools/1595901624-crypto-mcp/md5.md
- `sha224` — Read — https://policylayer.com/tools/1595901624-crypto-mcp/sha224.md
- `sha256` — Read — https://policylayer.com/tools/1595901624-crypto-mcp/sha256.md
- `sha384` — Read — https://policylayer.com/tools/1595901624-crypto-mcp/sha384.md
- `sha512` — Read — https://policylayer.com/tools/1595901624-crypto-mcp/sha512.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=1595901624-crypto-mcp · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/1595901624-crypto-mcp